Only if you have enough thrust to continue to climb/accelerate after aerodynamic lift drops off (ceiling alt.).

That is generally why winged things aren't used (yet). With the available best ISP, it is more efficient to blast off from the ground and accelerate thru the lower atmosphere as fast as you can. If you can extend the duration of your propulsion, even if it doesn't produce as much thrust, then the "flight" mode of assent becomes practical. Look into "Skylon" and the REL propulsion system.

I notised when briefly studied the subject that there is thin air still at 140 km altitude too...of 0.0000009 kg/m3...at 80 km there is 0.00018 kg/m3 and at 100 km 0.00006 kg/m3.

If you go fast enuf with huge wing area ( that is a must for solar powered flight in initial stage ) you could get there..aeroplanes need much less power to go high due to lift coefficient of the wing.

Altitude is less important than relative velocity. Altitude is just a consequence of orbital velocity, and on Earth a necessity to get above that pesky drag. Skylon is designed to achieve orbital velocity which is 7km/s of "speed". If you want to go elsewhere in the solar system you need escape velocity of 10.7km/s. You have to wind up at some where between those one way or another at MEKO, otherwise you are going back to mother earth.

I notised when briefly studied the subject that there is thin air still at 140 km altitude too...of 0.0000009 kg/m3...at 80 km there is 0.00018 kg/m3 and at 100 km 0.00006 kg/m3.

If you go fast enuf with huge wing area ( that is a must for solar powered flight in initial stage ) you could get there..aeroplanes need much less power to go high due to lift coefficient of the wing.

I cant remember the reference but I am fairly sure I once saw calculations that showed that above a certain height (below that of a 100km which is considered space) you would have to be travelling at above orbital velocity to get any positive aerodynamic lift from the very thin upper atmosphere so at some point if we ever do get SSTO spaceplanes they will have to transition between plane mode and traditional rocketry of some sort.

topspeed wrote:

I think SKYLON is made for rapid trasport on Earth...quite opposite what I am after.

And as he was once part of a project BlueStreak/BlackArrow/Prospero which did get Britain's only self launched satellite into space(and its still there occasionally going beep) at a price our allies the Americans thought we had missed a couple of zero's off at the time. I think there is a good chance he may succeed if he gets the money he needs. And as our launch space industry was cancelled so we could afford to join the French in developing Concorde I would not be surprised if Mr Alan Bond thinks rapid transport down here would be a distant second place application.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

Altitude is less important than relative velocity. Altitude is just a consequence of orbital velocity, and on Earth a necessity to get above that pesky drag. Skylon is designed to achieve orbital velocity which is 7km/s of "speed". If you want to go elsewhere in the solar system you need escape velocity of 10.7km/s. You have to wind up at some where between those one way or another at MEKO, otherwise you are going back to mother earth.

Yes I saw that the LEO altitude is not nearly out of the Earth yet.

The thing is that the low wing loading ac doesn't really know it is going mach one at 65 km or mach 4 at 90 km and mach 20 at 140 km...it just keeps on going faster and fasters and due to its large surfaces it is still responding like on sea level when doing just 50 km/h !

Amazing isn't it ?

This has lesser wing loading than Solar Impulse yet twice the power on solar. Just check how much fuel any AC spends just to get this high ( 20-25 km ).

This small craft could have instead of those two passengers a rocket that could be ignited at 25 km altitude..it could have 1 mass ratio still to go higher !

So if it is able to wind up to 25 km...and then have the possible top speed ( delta-v ) of 10 000 km/h ( in space )..I have a haunch it actually could hit the space. Am I right ?

I notised when briefly studied the subject that there is thin air still at 140 km altitude too...of 0.0000009 kg/m3...at 80 km there is 0.00018 kg/m3 and at 100 km 0.00006 kg/m3.

If you go fast enuf with huge wing area ( that is a must for solar powered flight in initial stage ) you could get there..aeroplanes need much less power to go high due to lift coefficient of the wing.

I cant remember the reference but I am fairly sure I once saw calculations that showed that above a certain height (below that of a 100km which is considered space) you would have to be travelling at above orbital velocity to get any positive aerodynamic lift from the very thin upper atmosphere so at some point if we ever do get SSTO spaceplanes they will have to transition between plane mode and traditional rocketry of some sort.

topspeed wrote:

I think SKYLON is made for rapid trasport on Earth...quite opposite what I am after.

And as he was once part of a project BlueStreak/BlackArrow/Prospero which did get Britain's only self launched satellite into space(and its still there occasionally going beep) at a price our allies the Americans thought we had missed a couple of zero's off at the time. I think there is a good chance he may succeed if he gets the money he needs. And as our launch space industry was cancelled so we could afford to join the French in developing Concorde I would not be surprised if Mr Alan Bond thinks rapid transport down here would be a distant second place application.

A lot of formula don't mention that they no longer work beyond some kind of phase change. For instance IIRC water increases in density as it cools but for some weird reason around 4C at standard pressure it flips on a weird S shaped curve and that's why ice floats rather than sinks to the bottom of rivers and ponds.

Even tho I can't remember the reference I can remember the reasoning which seemed sound to me and still does. If you forget all the complex theory around flight like the Bernoulli's principle, pressure differentials etc. etc. Flight is basically a Newtonian balancing of forces, you are throwing a bit of the atmosphere away from you downwards with sufficient force to cancel out the force of gravity acting on your plane. Now you can either throw a lot of air slowly or a small amount very fast to get the same effect. But if the air is very thin then the amount of air bouncing off your plane downwards is not enough to lift you against gravity unless its already going above orbital velocity so QED you cant use lift to get to orbital velocity.

topspeed wrote:

I have not the pleasure to know Alan Bond.

I only met him once briefly at some kind of tech show many years ago and talked about HOTOL I think the stand was being used to try and raise funds for reaction engines at the time IIRC. I cant remember the name of the show but I really got the impression he wanted to get into space not provide a faster commuting vehicle for yuppies

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

But I would not throw away perfectly working formulas lightly. Air is air..no matter how high it was.

I am not throwing away a formula but you have to be aware that some work only within a range of parameters and I was pointing out where it broke down. And no at great height air changes from a gas to more of a plasma hence the northern and southern lights and as I pointed out earlier you can have different formulas for the properties of liquids and solids(water and ice) the same goes for gases and plasmas even tho some of the formulas have similar properties those for turbulence etc. But even without the complexities of phase changes I pointed out how the problem can be reduced to simple Newtonian physics the plane has to be able to accelerate a mass of air downwards fast enough to counter the weight of the plane as you get higher the air gets thinner so you would have to accelerate the small mass available faster. The law of diminishing returns trumps the flat edges of the bell curve of most formulas 9 times out of 10 I am sorry to say. Much as I would like cheap space flight you are not going to get it with a purely lift based plane you will need some kind of rocketry effect as well even if its only a solar powered ion drive accelerating the last wisps of the atmosphere at relativistic velocity's.(and that would need a very good power to weight ratio)

If you're interested in climbing to space using lift, check out JP Aerospace. They're planning on using a hybrid airship, starting from a high altitude.

You can, of course, opt for a mixed propulsion system using chemical boosted by electric. If the contribution from both is equal, you'll get a 40% boost in Isp (and thrust) over chemical alone. Or you could use a solar thermal rocket and add in oxidiser to boost the thrust.

Roger that SANEAlex..how much ION drive thrust do I get with 10 000 watts ?

That very much depends on the efficiency your ion drive with lots of factors to take into account but here are some numbers for you to play with if you want to do the hard math looking at one of my crib sheets the minimum amount of energy to accelerate 1Kg of mass from ground to escape velocity not counting atmospheric or gravitational drag is 62.4 Mega Joules/17.8 Kilowatt Hours.

topspeed wrote:

I am sure the pilot who drives the vehicle may develope a technique how to fly it to the top ( for instance 150 km ).

He/she may accelerate the ship at 100 km into high speed ( mach 8 for instance ) and then it just goes ballistic like rocket at 45 deg angle till the fuel runs out.

There is a difference between orbital velocity where you get to stay up and suborbital hops where you can go up quite high and then fall back down.

topspeed wrote:

Do you agree that the FAI prop altitude record of 17 500 meters can be broken with lighter yet more efficient machine ?

With improvements with materials technologies I would not be surprised at incremental increases of the record but there will still be a fundamental limit where the various bell curves of materials properties hit unobtainium limitations. Unless of course CERN finds out that antimatter is repelled by gravity then you will only have to wait a few million years while they produce enough to make a magnetically shielded vehicle and a few million more years while you wait for the health and safety permissions to fly that much AM in the atmosphere of an inhabited planet

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

If you're interested in climbing to space using lift, check out JP Aerospace. They're planning on using a hybrid airship, starting from a high altitude.

You can, of course, opt for a mixed propulsion system using chemical boosted by electric. If the contribution from both is equal, you'll get a 40% boost in Isp (and thrust) over chemical alone. Or you could use a solar thermal rocket and add in oxidiser to boost the thrust.

This is the second time this week someone mentions JP Aerospace...I will.

Roger that SANEAlex..how much ION drive thrust do I get with 10 000 watts ?

That very much depends on the efficiency your ion drive with lots of factors to take into account but here are some numbers for you to play with if you want to do the hard math looking at one of my crib sheets the minimum amount of energy to accelerate 1Kg of mass from ground to escape velocity not counting atmospheric or gravitational drag is 62.4 Mega Joules/17.8 Kilowatt Hours.

topspeed wrote:

I am sure the pilot who drives the vehicle may develope a technique how to fly it to the top ( for instance 150 km ).

He/she may accelerate the ship at 100 km into high speed ( mach 8 for instance ) and then it just goes ballistic like rocket at 45 deg angle till the fuel runs out.

There is a difference between orbital velocity where you get to stay up and suborbital hops where you can go up quite high and then fall back down.

topspeed wrote:

Do you agree that the FAI prop altitude record of 17 500 meters can be broken with lighter yet more efficient machine ?

With improvements with materials technologies I would not be surprised at incremental increases of the record but there will still be a fundamental limit where the various bell curves of materials properties hit unobtainium limitations. Unless of course CERN finds out that antimatter is repelled by gravity then you will only have to wait a few million years while they produce enough to make a magnetically shielded vehicle and a few million more years while you wait for the health and safety permissions to fly that much AM in the atmosphere of an inhabited planet

Heard of the nanocellulose ?

1 kilo to escape velocity is something in an efficient aeroplane..have to see to that too.